process-wrapper.c

// weibo上有人说到https://github.com/joewalnes/websocketd，我想其原理大致如此（process-wrapper.c）:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

int wrap_process(const char* exefile) {
    int status;
    pid_t pid;
    char* output_file = "./wrapped-output.txt";
    int output_fd;

    output_fd = open(output_file, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
    if (output_fd == -1) {
        return -1;
    }

    pid = fork();
    if (pid < 0) {
        return 0;
    }
    else if (pid == 0) { // child process
        dup2(output_fd, 1);
        close(output_fd);

        execlp(exefile, exefile, NULL);
        exit(0);
    }
    else { // parent process
        waitpid(pid, &status, 0);
        return 0;
    }
}

int main(int argc, char *argv[]) {
    int ret;

    if (argc != 2) {
        printf("Usage: ./process-wrapper $PROG_NAME");
        return -1;
    }

    ret = wrap_process(argv[1]);

    exit(ret);
}